Update documentation for ACCESS regional model beta release

[atteggiani]

For the Beta release of the ACCESS regional model, the following tasks should be addressed within the related draft PR:

• Content should be added to the ACCESS-RAM configuration overview detailing the configuration specifications.
  An example can be taken from the [ACCESS-ESM configuration page], including the presence of two different suites and their purpose, the components used, nesting levels, what is a nesting, and any additional information useful for the specific configuration.
• The How to run ACCESS-RAM page should be updated based on the reviews of the related PR above.